Pretty sure Vlad didn't let people know what his sphere was through horribly written descriptions or directly telling people about the sphere. I am sure he did it by RPing in a manner that his sphere choice was made clear to those around him. This is how this should be conveyed in the game.

As for sphere's while they aren't the only way to do it, they aren't a bad way to help build into the game some guides for RP. Personaly the only time I run into any trouble with them is if I don't put anything thought into a character before I create it and I don't think the game should be redesigned to fix my lack of forethought.